1. Field of the Invention
The present invention relates to a liquid crystal display device in which a protection plate in a liquid crystal panel has an additional function.
2. Description of the Related Art
Generally, a liquid crystal display device includes a backlight (a backlight carrier including a backlight), a reflective plate, a light guide plate (a light guide), a diffusing plate, a liquid crystal panel, and a protection plate for protecting the liquid crystal panel. The backlight, the reflective plate, the light guide plate, the diffusing plate, and the liquid crystal panel are provided in a support frame such that the backlight is placed on a backside and the liquid crystal panel is placed on an upper side, so as to form a liquid crystal module (a conventional liquid crystal module). Then, the liquid crystal module is attached to a mother device, and the protection plate is attached thereto so as to cover its upper side (a surface of the liquid crystal panel). The liquid crystal display device is arranged as such. For example, in a mobile phone including a liquid crystal display device, a liquid crystal module is placed in a mother device of the mobile phone, and a protection plate for protecting a surface of the liquid crystal panel is attached to the mother device. In this way, the conventional liquid crystal display device is arranged such that the liquid crystal module including the liquid crystal panel and the protection plate for protecting the surface of the liquid crystal panel are, so to speak, provided separately from each other and respectively attached to the mother device.
The protection plate is a necessary member for a liquid crystal display device in order to protect a liquid crystal panel from an external force. Meanwhile, in recent years, it has been proposed to add an additional function other than the protection function to the protection plate. For example, a specific phase characteristic is added to the protection plate so that contents displayed in the liquid crystal panel become invisible or unable to be peeked at from the side so to a provide a viewing angle control function, and a protection plate is resonated so as to output sound so as to provide an audio function. See, for example, Japanese Translation of PCT International Application, Tokuhyohei, No. 11-512253, and Japanese Unexamined Patent Publication, Tokukai, No. 2000-152385.
In such a case where the protection plate has an additional function other than a protection function for the liquid crystal panel, and as a result, the liquid crystal panel becomes closely related to the protection plate, the conventional arrangement in which the liquid crystal module and the protection plate are separately provided causes a problem that the additional function is insufficiently realized.
More specifically, it is required to perform alignment to the liquid crystal panel and the protection plate in regard to the viewing angle control, and it is required to set an acoustic characteristic according to an arrangement of the liquid crystal module including the liquid crystal panel in regard to the audio function. However, in the conventional arrangement in which the liquid crystal module and the protection plate are respectively attached to the mother device, such alignment and setting cannot be appropriately performed.